Craftsmanship and material belong together
The most important material at the Freiburg Sandalenwerkstatt is leather. Sturdy, hard-wearing leather for our sandals, selected qualities for our bags. We work closely with our tanneries and search very carefully for the leather that best suits each particular task. There is much to consider, as the type of leather, the tanning process, the dyeing and finally the greasing can result in very different properties — from firmness to appearance.
What does vegetable-tanned leather mean?
Vegetable-tanned leather — also called bark-tanned, vegetably tanned or traditionally tanned — is processed exclusively with natural tanning agents from tree bark, leaves and fruits. In contrast to chrome tanning, which accounts for around 80 percent of worldwide leather production today, vegetable tanning requires above all one thing: time. The hides go through various wet processes for weeks, sometimes months, until they have become real leather.
The vast majority of the leather we process at the Sandalenwerkstatt is vegetable-tanned. For a few exceptions, we use combination-tanned leather, where mineral tanning agents are used alongside vegetable tannins. Neither one nor the other is a quality feature in itself — what matters is the work and skill of the tanners.
Pit tanning and oak bark: The most traditional method
A special variant of vegetable tanning is pit tanning with oak bark. The hides are layered in large pits and covered with ground oak bark. This process is extremely slow — a complete tanning cycle can take up to twelve months. The result is a firm, long-lasting leather with a suppleness that industrially tanned leather rarely achieves.
We source our leather from, among others, two tanneries in Tuttlingen: the Martin tannery, which has been producing sole leather using pit tanning since 1645, making it one of the oldest tanneries in Central Europe, and the Rotgerberei August Renz, which has been producing vegetable-tanned leather for five generations. At Renz, some of the heavy cowhides are tanned more quickly in rotating drums with higher concentrations of vegetable tanning agents — a process better suited to certain leather qualities.
Nose to tail: Why leather is a sustainable material
Nose to tail is a term from the kitchen, but the idea behind it also applies to leather production. With animal products, the ecological footprint improves when truly everything is used. The hide of an animal can be a high-quality product — if it comes from a good tannery and is carefully processed.
Compared to plastic sandals, which consist of various materials and are hardly repairable, vegetable-tanned leather has clear advantages: it is repairable, long-lasting and made from a renewable raw material. The tanning agents used are of natural origin, and the leather is biodegradable. Those who prefer not to use animal products will find alternatives in plastic sandals — but must then accept the disposal problem and the use of mineral oil as a raw material.
Different qualities for different tasks
How high-quality a leather becomes depends largely on the work of the tanners and the raw material. Our tanneries select the hides from regional livestock farming according to clear criteria and produce different qualities from them.
For the sole construction of our sandals, we need firmer and thicker leather. For the straps and as top leather on our clogs, we use more supple leather. The leather for our bags is already dyed and further processed at the tannery — for example, heavily greased into pull-up leather, as we use for our Cartridge Bags.
We buy whole hides and cut them ourselves. For our sandals and shoes, we dye the straps and insoles with aniline dyes, grease the finished parts with quality leather fat and polish them by hand. The leather that comes from the tanneries is therefore not yet the finished product. Only when we further process it in the workshop does it acquire the properties that perfectly suit our sandals and shoes.
For our bags, the tanneries take on more preparatory work. Dyeing entire suede hides or heavily greasing leather works much better at the tannery than in our small workshop. We can always rely on the quality of our tanneries.
Character and patina: Leather that evolves
We particularly appreciate the character of vegetable-tanned leather. It is extremely skin-friendly — only very few people react sensitively to the natural tanning agents that remain in the leather to a certain degree. And they should, after all, they are what turn the hide into leather in the first place.
When worn, vegetable-tanned leather changes slowly. It develops, depending on how it is used and cared for. The colour tone may shift over time, the surface becomes softer and more supple. This is entirely typical and intentional. In this sense, the wearer always contributes to the appearance of our sandals. You can see it in the patina — and that is actually a beautiful thought.
